Cellulose organic derivative composition of matter containing beta-ethoxy ethyl lactate



Patented Oct. 25, 1932 UNITED STATES.

PAT-TENT OFFICE HENRY B. SMITH, OF ROCHESTER, NEW YORK, ASSIGN OR TOEASTMAN KODAK COMPANY, v

OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK CELLULOSE, ORGANICDERIVATIVE COMPOSITION OF MATTER CONTAINING B-E'rHoxY *ETBYI. ,LACTA'IE'No Drawing. 1

This invention relates to compositions of matter in which celluloseorganic derivatives, such as cellulose acetate or cellulose ethers, arecombined ormixed with other substances,

1 such as a compatible plasticizer, with or without a common solvent forboth, and with or without other useful addition agents, so that theresulting product will have properties such as will make the compositionhighly advantageous for use in the plastic and analogous. arts, such,for instance, as the manufacture of wrapping. sheets or tissue,photographic film, molding compounds and products, artificial silk,varnishes or lacquers, coating compositions and the like.

One object of this invention is to produce a composition of matter whichmay be made into permanently transparent, strong and flexible sheets orfilms of desired thinness which are substantially waterproof, areunaffected by ordinary photographic fluids and possess the desiredproperties of a support for sensitive photographic coatings Another object. of my invention is to produce a composition of matter which iscapable of easy and convenient manipulation in theplastic and analogousarts, such as in the manufacture of sheets, films, artificial silkfilaments, varnishes, lacquers and the like, and to produce acomposition which will not injure, or

be injured by, the substances or surfaces with V which it is associatedduring manufacture. Another object of my invention is to producecompositions which can be molded at elevated temperatures and highpressures to produce plastic products having the desirable properties ofcelluloid. Still another object of my invention is to producecompositions of matter containing cellulose acetate which have a highdegree of flexibility, softness, pli ability and clarity. Other objectswill become apparent to those skilled in the art to which this inventionpertains.

While cellulose acetate has been known for decades, it has also beenknown that to utilize it in various plastic arts it is necessary to mixtherewith such plasticizing or conditioning agents as triphenyl 7phosphate, monochlornaphthalene or the like. Certain of these and otheraddition agents are also Applicationiflled lugust 10, 1931. Serial No;556,828.

added for the purpose of reducing the inflammability of the product.Plastic inducing agents, such as the higher alcohols and their esters,are sometimes also added. Similarly, addition compounds of various kindshave been employed to increase flexibility, transparency, toughness andother properties which will enhance the value of the resulting product.Addition products for the same or similar purposes are also added tocellulose acetate to prepare it for use in the other plas of desirableproperties required ,of cellulose acetate for most purposes have madethe discovery of new and economical plasticizersor other addition agentsa matter of consider-,

able importance to the art. This has been a problem of some difficulty,since many of the nitrocellulose solvents are not solvents for celluloseacetate, and many substances which act as plasticizers fornitrocellulose are not sufficiently compatible with cellulose acetate tobe used as plasticizers in cellulose acetate compositions.

I have discovered that valuable properties I thereto as a plasticizingcompound a B-alkoxy ethyl lactate, such as B-ethoxy ethyl lactate. Thiscompound has the formula The particularly useful properties which it lidture is heated to distill the water formed in the reaction. Someethylene glycol mono ethyl ether goes over also. Sodium carbonate isadded from time to time to the ethylene glycol monoethyl ether-watermixture, and the ethylene glycol monoethyl ether which separates isreturned occasionally to the reaction mixture. IVhen 250 g. of water hasbeen collected,the reaction mixture is distilled under reduced pressure.TheB-ethoxy ethyl lactate distills over at 100-102 C. at 16 mm.pressure. a V

In order that those skilled in this art may better understand myinvention I would state, by way of illustration, that for themanufaeture of photographic film or other sheets my newcomposition ofmatter may be compounded as follows: 100 parts of acetone-solublecellulose acetate, i. e. cellulose acetate containing from 36% to 42%aeetyl radical, approximately, is dissolved with stirring at atmospherictemperature in 300 to 500 parts,

, film-forming surface to form a film or sheet,

in'a manner well known to those skilled in the art. A film so producedhas permanently brilliant transparency (even where as much as 50 toparts of B-ethoxy ethyl lactate per 100 parts of cellulose organicderivative, such as cellulose acetate, is used) and low inflammability,burning no more readily than ordinary newsprint. Films or sheetsproduced in accordance with my invention are quite tough and flexible.For instance, films of cellulose acetate plasticized with 30% to 50%(parts-by weight based on the acetate) of B-ethoxy ethyl lactate had aninitial flexibility of from 25% to greater than that of film containingno plasticizer. Furthermore, film so plasticized maintains flexibilityin a superior fashion. For instance, films containing 20% and 30% ofB-ethoxy ethyl lactate maintained flexibility at 65 C. for 135 days and170 days, respectively, whereas an unplasticized film became brittle in30 days. This demonstrates that film so plasticized will withstandordinary usage satisfactorily for many years. The sum total of the aboveadvantageous properties of products produced from my new compositions isconsiderably in excess of that of products produced with what havepreviously been regarded as the better plasticizers.

Other similar solvents (instead of acetone) which are compatible withthe cellulose acctate and my new plasticizers may also occur to thoseskilled in this art. In like manner these plasticizers may be compoundedwith other single organic esters of cellulose, such as cellulosepropionate, butyrate and the like, or with mixed organic and/ orinorganic esters such as cellulose aceto-stearatc, celluloseaceto-propionate, cellulose aceto-malate, orcellulose nitro-acetate, orwith cellulose ethers, a suitable solvent which will dissolve both thecellulosic derivative and the plasticizer being employed.

Inasmuch as my above described compositions of matter are quite usefulin the production of films and sheets, it will be apparent that my newplasticizers may also be employed with advantage in the other branchesof the plastic art. For instance, my above described compositions ofmatter may be employed in the manufacture of artificial silk by the dryspinning method. With the proper coagulating bath they may also beemployed for wet spinning. It may be desired to employ compositions ofdifferent viscosity or evaporation characteristics, but this IS a merematter of changing the solvent proportion or adding evaporationretardents or other high or intermediate boiling constituents, as hasbeen well known in the art for more than a decade. My novel plasticizersmay also be employed with advantage in connection with a number of theknown lacquer and varnish formulae with which they may be found to becompatible. In such cases the it plasticizer is usually first put intosolution in the cellulose derivative solution, and if non-solvents areadded for the purpose of cheapening the composition they are added onlyto such an extent as will not precipitate the derivative from solution.Also the plasticizer is usually employed in larger amounts, such as from50 to 60 parts, in compounding lacquers. Other uses within the scope ofmy invention will also suggest themselves to those skilled in the artand are to be included within the scope of the claims appended hereto.

B-ethoxy ethyl lactate may also be advantageously used as a plasticizerin cellu lose acetate molding compositions. For instance, when fromabout 20% to 40% (parts by weight based on the cellulose acetate) ofB-exthoxy ethyl lactate is homogeneously mixed with cellulose acetate,the mixture may be converted into a hard, translucent plastic product bymolding at. a temperature of 140 to 160 C. and'a pressure of from 2000to 5000 pounds per square inch for a period of from 2 to 5 minutes, in amanner already known to those skilled in molding compounds of thatnature.

Moreover, I have found that, upon the addition to cellulose acetate ofapproximately of B-ethoxy ethyl lactate, quite unexpected compatibilityof the plasticizer with the cellulose acetate exists, and also thatquite unexpected flexibility and plasticity of the final productresults. Contrary to experience in most cases where such a largeproportion of plasticizer is used, no exudation or crystalhzing out ofthe plasticizer occurs. In fact this plasticizer may be used in almostany proportion with cellulose acetate, since it is a solvent for it.

Such compositions have great utility where a highly flexible compound isdesired, such as in the coating of a base (for instance, cloth or otherfabric) in the production of artificial leather or the production ofrelatively thin sheets wherein more than the usual flexibility isimportant. Such a composition, ifconverted, for instance, into sheetform will be found to be supple and nonrigid, and to have the ability toconform readily to a surface upon which it may be placed, and this evenat atmospheric temper- V atures These novel compositions of matter areproduced by merely mixing the plasticizer with cellulose acetate andthen adding sulficient of a common solvent, such as acetone, whereuponan intimate mixture of the plasticizer with the cellulose acetateresults. The amount of acetone or other common solvent to be employedvaries, of course, within rather wide limits depending upon the fluidityof the composition desired. |100 parts of acetone will sufiice for manypurposes, although we prefer to use 400 parts. Various high boilers orevaporation retardents, such as ethyl lactate, amyl acetate or the likemay also be added if desired, as is well known in this art.

The compositions of matter so produced may then be coated into sheets inthe usual way by depositing them upon plates or rolls and permitting thesolvent to evaporate. If

my novel compositions are to be employed in the manufacture ofartificial leather, they may be coated upon, for instance, a clothsupport and the solvent permitted to evaporate, or the cloth support maybe caused to pass through the cellulose acetate-plasticizer compositionand permitted to absorb the solution, the solvent in the coating beingthen permitted to evaporate. In either case,

the solvent may, of course, be recovered if desired by condensing thevapors, etc.

While above and in certain of the claims appended hereto, I havereferred to the use of a plasticizer in approximately equal proportions,namely in a ratio of approximately 100%, it will be understood thatwithin this terminology variations of from 10% to 15% less than 100% ofplasticizer and as much as 25% to 50% more than 100% of the plasticizermay in some instances be desirable.

What I claim as my invention and desire to be secured'by Letters Patentof the United States is:

1. A composition of matter comprising an organic derivative of celluloseand a B-ethoxy ethyl lactate.

2. A composition of matter comprising cellulose acetate andB-ethoxyethyl lactate.

3. A composition of matter comprising 100 parts of cellulose acetate andabout 10 to 100 parts, by weight, of B-ethoxy ethyl lactate.

4. A relatively thin sheet comprising 100.

parts of cellulose acetate and about 10 to 100 parts, by Weight, ofB-ethoxy ethyl lac high pressures, comprising 100 parts of' celluloseacetate and approximately 20 to 50 parts, by weight of B-ethoxy ethyllactate. Signed at Rochester, New York, this 31st day of July, 1931.

HENRY B. SMITH.

